1. Field of the Invention
This invention relates in general to a soldering means including at least one stirrup electrode that can be heated by electrical resistance and can be used particularly for soldering high-pole electronic components on PC boards.
2. Description of the Related Art
German DE 31 49 236 discloses an electrode holder and soldering means which comprises small columns composed of electrically conducting material which are electrically insulated from each other with at least two stirrup electrodes being fastened in interchangeable fashion between their ends. The U-shaped stirrup electrodes which can be heated by electrical resistance are formed from a flat plate composed of resistive materials such as tandulum or molybdenum and are fastened in a manner so that they come in contact with the elements which are being soldered at their bottom edge of their soldering strip surface. When a plurality such as two or four stirrup electrodes are used together, four small columns are necessary for the electrode holders and the columns are arranged on a respective diagonal of the soldering means and are mechanically connected with each other by several cross-shaped cross-strut diagonal members. The power supply of four strip-shaped electrodes comprise two small columns located on one diagonal which are connected with one pole of a current source and two other small columns are connected to the other pole of the current source.
German DE-A-28 18 958 discloses a different soldering means in which the electrode holder comprises two small columns composed of conductive material which are electrically insulated from each other and between their ends one single strip electrode is fastened. This stirrup electrode comprises a total of four soldering strips which have the shape of one-piece rectangular frame and two oppositely located soldering strips are fastened in an exchangeable manner or extensions on the associated small columns which project toward the top of the device.
European Patent EP-A-O 011 046 discloses another soldering means which has one single stirrup electrode fastened to an electrode holder which has altogether four soldering strips located opposite from each other in pairs and the soldering strips have the shape of a one-piece rectangular frame.
These known soldering means described above are used particularly for soldering high pole electronic components such as micropacks, flatpacks and so on to printed circuit boards and the stirrup electrodes are resistively heated by current pulses. It is necessary before soldering as well as during the entire duration of the soldering that good contact be assured between the operating surfaces of the stirrup electrodes and the contact legs of the components and the inner connections or contact pads of the PC board. However, even if the soldering strips are adjusted so that they are absolutely parallel to the soldering joint this requirement cannot always be assured.